If your Z-Pro is the same case (I believe it is) as the 6850 IntelliStation M-Pro, another part number you could look for is 09N4300, but please do not hold me to it. From the description given, the kit turned the IntelliStation on its side and added brackets to screw it into a rack mount.

Unless you have several of them, the question is why?

Best bet for finding them is to go to a smaller university and check their computer science department. They may be getting rid of the older IntelliStations for newer servers. There is a Tower to Rack Conversion Kit (09N4300) for a prohibitive cost (as well as being located in Hungary) on eBay.